Customize how priority maps from Remember The Milk to Outlook

When using MilkSync the first three priorities map directly, but the "none" priority is weird. Any tasks with no priority in RTM turn into normal priority in Outlook, just like the medium priority tasks. Syncing the other direction there's no way to create a task with no priority from Outlook.

My proposed solution is to have a setting that determines how the priorities map. I don't know if this should be specified per account, per list or per client, but the more specific it was the more flexibility it would allow me to interpret those priorities as I like.